Ibn al-Qayyim (may Allah have mercy on him) in Lahfaan: “The Messenger of Allah (peace be upon him) ordered the demolition of the damage mosque, in this guide to demolish what is the greatest havoc from mosques built on graves, the rule of Islam in which to demolish the whole even settled Earth, the first demolition of the damage mosque, as well as the domes on the graves, which must all be demolished; because it is based on the sin of the Prophet

ISIS also removed the crosses from the Chaldean and Orthodox churches and replaced them with the Islamic flag.Jihad Watch reported:Al Arabiya reported:

Jihadists who overran Mosul last month have demolished ancient shrines and mosques in and around the historic northern Iraqi city, residents and social media posts said Saturday.

At least four shrines to Sunni Arab or Sufi figures have been demolished, while six Shiite mosques, or husseiniyahs, have also been destroyed, across militant-held parts of northern Nineveh province, of which Mosul is the capital.

Pictures posted on the Internet by the Islamic State of Iraq and Syria (ISIS) showed the Sunni and Sufi shrines were demolished by bulldozers, while the Shiite mosques and shrines were all destroyed by explosives…

…An employee at Mosul’s Chaldean cathedral said militants had occupied both it and the Syrian Orthodox cathedral in the city after finding them empty.

They removed the crosses at the front of the buildings and replaced them with the Islamic State’s black flag, the employee said.

ISIS-led militants overran Mosul last month and swiftly took control of much of the rest of Nineveh, as well as parts of four other provinces north and west of Baghdad, in an offensive that has displaced hundreds of thousands and alarmed the international community.